AIDS is transmitted by sexual encounters, by transfusion of infected blood and from mother to neonate, either in utero or by colostrum and milk. The genitourinary tract and breast are tissues which are protected by the mucosal immune system. It is important to consider induction of effective immunity to simian and ultimately human immunodeficiency viruses (SIV/HIV) at mucosal sites, where the natural transmission may occur. Cytotoxic T lymphocytes (CTLs) are important in elimination of virally infected cells, and any studies of mucosal immunity must consider the induction of SIV/HIV specific CTLs at local sites. It is known that oral immunization with virus will induce specific CTLs in Peyer's patches (PP) and potentially in effector regions, e.g., lamina propria lymphocytes (LPL) and in the intraepithelial lymphocyte (IEL) subset. It is also known that HIV-specific CTLs occur in AIDS and CD3+, CD8+ CTLs suppress viral replication and lyse HIV-infected targets. This grant application will thus focus on induction and characterization of CTL responses to SIV in rhesus macaques orally (or systemically) immunized with SIV components in antigen-delivery systems. To do this, monoclonal anti-rhesus CD3 (rCD3) will be made to allow characterization of SIV-specific CTLs and development and characterization of CTL clones. In addition, rCD3+, CD8+ CTLs from macaques will be mainly assessed from peripheral blood mononuclear cells (PBMC) following infection through vaginal/urethral routes. In some experiments, CTL activity will be examined in T cells isolated from mucosal tissues of biopsy specimens. Further, rCD3+, CD8+ CTLs will also be studied in macaques orally immunized with whole SIV or components in microcapsules, to determine if effective CTLs are induced in PBMC. When effective CTLs are induced in PBMC of orally-immunized primates, we will then examine whether SIV-specific CTLs are induced in mucosal tissues of macaques given oral SIV vaccine. We will subsequently derive rCD3+, CD8+ CTL clones from macaques orally immunized with the optimal vaccine to determine the mechanisms involved in CTL-induced anti-SIV immunity. These studies will provide important new information regarding the induction of functional SIV-specific CTLs in PBMC and mucosal tissues by appropriate oral immunization.